| LIU Zhi-hua,GAN Li-qin,LIU De-e,RONG-hui.Effect of Sulfur-oxidizing Bacteria on Concrete Properties in Seawater Environment[J],52(11):280-290, 317 |
| Effect of Sulfur-oxidizing Bacteria on Concrete Properties in Seawater Environment |
| Received:September 22, 2022 Revised:February 27, 2023 |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2023.11.022 |
| KeyWord:sulfur-oxidizing bacteria biofilm concrete microstructure macroscopic properties |
| Author | Institution |
| LIU Zhi-hua |
School of Materials Science and Engineering,Tianjin , China;Tianjin Key Laboratory of Building Green Functional Materials, Tianjin Chengjian University, Tianjin , China |
| GAN Li-qin |
School of Materials Science and Engineering,Tianjin , China |
| LIU De-e |
School of Materials Science and Engineering,Tianjin , China;Tianjin Key Laboratory of Building Green Functional Materials, Tianjin Chengjian University, Tianjin , China |
| RONG-hui |
School of Materials Science and Engineering,Tianjin , China;Tianjin Key Laboratory of Building Green Functional Materials, Tianjin Chengjian University, Tianjin , China |
|
| Hits: |
| Download times: |
| Abstract: |
| Microbial corrosion is a widespread problem in nature, and the construction industry is included, particularly in microbial-rich areas such as sewage treatment facilities and marine buildings. Microbial growth in different environments will have different significant effects on the microstructure and macroscopic properties of concrete, but there appears to be no published literature on the effects of sulfur-oxidizing bacteria on concrete properties in a seawater environment. In this study, concrete specimens were semi-submerged in seawater containing microorganisms, and the changes in biofilm thickness and the number of microorganisms within the film at the gas-liquid-solid interface of concrete at different corrosion ages was analyzed with an optical microscopy and ultraviolet optical density (OD). The evolution of the surface morphology of concrete was recorded with a general video camera, a VHX-600e ultra-deep field microscope, a YAW-2000J pressure tester and scales to test the changes in compressive strength and mass of concrete specimens, and a NJ-DTL-6 concrete chloride ion electric flux tester was used to measure the electric flux of concrete specimens. Samples were also taken at the gas-liquid-solid interface of the concrete specimens and the microstructure of the concrete was analyzed and tested with a Q600 simultaneous thermal analyzer, a Rigaku ultima-V1 X-ray diffractometer, a Tensor 27 Fourier transform infrared spectrometer (FTIR) and an Auto Pore V 9600 mercury compression meter. A cyclical pattern of growth, development and shedding of biofilms could be found, starting at around 30 days, entering a rapid development phase after 60 days, maturing to a peak thickness of 2 200 µm at 120 days and then starting to shed until the next growth cycle at 150 days, with a positive correlation between the number of microorganisms in the membrane and the thickness of the biofilm. The results of the macroscopic properties of the concrete showed that the electric flux of the concrete in the sterile group reached 793.1 C at 120 days, while the electric flux of the concrete in the bacterial group was only 173.4 C. At 180 days, the concrete in the sterile control group cracked with a crack width of 0.11 mm, while no cracks were produced in the concrete in the bacterial test group. The compressive strength of the bacterial concrete increased by 6.9% while that of the aseptic concrete decreased by 7.1%. The results of the micro-structural tests on the concrete showed that the gypsum production and C-S-H gel loss of the concrete in the bacterial group were less than that of the aseptic concrete, and the porosity of the concrete in the bacterial group was 1.193 5% lower than that of the aseptic concrete. It can be concluded that sulfur-oxidizing bacteria attached to the gas-liquid-solid interface of the concrete gradually form biofilms, with periodic changes in the thickness of the film and the number of microorganisms within it. Sulfur-oxidizing bacteria and their biofilm have a protective effect on the microstructure of the concrete. The negatively charged nature of the sulfur-oxidizing bacteria repels the migration of SO42‒ from the medium to the concrete and the dense nature of the biofilm also leads to a reduction in the mass transfer efficiency of SO42‒, thus slowing down the erosion of SO42‒ into the concrete. |
| Close |
|
|
|